Need solution for this error

at the first i used Cache to show data than everything was working, but after a while the cache were gone so then same issue page is not found, so i removed cache, after removing the cache the same probem again, 404 not found, than used some command, like route, views, config: clear, optimize:clear, and optimize clear, than it was working fine,,,, after that i created the contact part, af ther creating the same problem again nothing was working but after that i again run those command and still not working,,, but in the backend everything is working perfectly,,

in the backend i used this return view('backend.about-us.index')->layout('backend.layouts.app');

and in the front end i used this return view('frontend.contact.index'); so how am i going to solve the error